Portable electronic device

ABSTRACT

When image data is displayed on the display portion of a conventional mobile telephone, characters cannot be displayed thereon, and thus the image data and the characters cannot be simultaneously displayed. In a portable electronic device according to the present invention, a cover member having a first display device ( 101 ) for displaying an image (digital still image or the like) and a second display device ( 102 ) having a touch input operational portion (for displaying characters, symbols, or the like) are attached to each other so as to allow opening and closing.

This application is a continuation of U.S. application Ser. No.13/079,552, filed on Apr. 4, 2011 now U.S. Pat. No. 8,405,790 which is acontinuation of U.S. application Ser. No. 12/239,138, filed on Sep. 26,2008 (now U.S. Pat. No. 7,920,215 issued Apr. 5, 2011) which is acontinuation of U.S. application Ser. No. 09/934,699, filed on Aug. 22,2001 (now U.S. Pat. No. 7,430,025 issued Sep. 30, 2008).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a portable electronic device having adisplay portion with a circuit composed of thin film transistors(hereinafter referred to as TFTs), for example, a portable electronicdevice equipped with a display device such as a liquid crystal displaypanel as the display portion.

Note that the portable electronic device in this specification means aportable information processing device in general, and includes a mobiletelephone, a mobile television telephone, a portable computer, and thelike.

2. Description of the Related Art

Conventionally, in a mobile telephone, one liquid crystal display deviceis normally used as the display portion. Further, because of a demandfor miniaturization, there is a limitation to the size of the screen ofthe display portion.

Also, recently, the communication technology has progressed, and thussending and receiving of electronic mails and access to home pages onthe Internet can be made by using the mobile telephone.

Recently, although it is possible to send and receive of electronicmails by the mobile telephone, communication with only characters in atext form is possible. Thus, even when a message to which image data isattached by, for example, a personal computer or the like is received,the image data cannot be displayed on the display portion of the mobiletelephone.

Also, even in the access to a home page on the Internet, image data onthe home page cannot be displayed on the display portion of the mobiletelephone.

Display of characters (text) or a simple image is sufficient in adisplay portion of a conventional mobile telephone. Thus, it is notnecessary to use a high resolution display portion. Also, it is notnecessary to use a full color display portion.

However, since it has been possible to communicate by electronic mailsof the mobile telephone in recent years, a high resolution and fullcolor display portion is greatly required. Among various mobiletelephones, although a mobile telephone capable of displaying image datahas been on sale, many mobile telephones have two-color display such aswhite and black. Thus, although there is the case where the full colordisplay portion is used, image quality is low and it is difficult to seethe image.

Also, when the image data is displayed on the display portion, thecharacters (text) cannot be displayed thereon. That is, the image dataand the characters (text) cannot be simultaneously displayed.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a portableelectronic device comprising:

a first display device for displaying an image; and

a second display device having a touch input operational portion,

wherein the first display device and the second display device areattached to each other in a longitudinal direction or in a lateraldirection. Note that in the electronic device shown in FIG. 2, the firstdisplay device and the second display device are attached to each otherin the longitudinal direction.

In another aspect of the present invention, there is provided a portableelectronic device comprising:

a cover member having a first display device for displaying an image:and

a second display device having a touch input operational portion,

wherein the cover member and the second display device are attached toeach other so as to allow opening and closing. Note that in theelectronic device shown in FIGS. 1A to 1C, the cover member and thesecond display device are attached to each other so as to allow openingand closing.

Also, the configuration as shown in FIGS. 3A to 3C, that is, a thirddisplay device may be provided between the cover member and the seconddisplay device. A fourth display device and a fifth display device maybe provided to increase the number of screens and thus the displayregion may be expanded. The third display device may be equipped with animage pickup device or a sensor. Also, the third display device may beequipped with a system for identifying the user.

Also, in the above structures, not only the second display device butalso the first display device may be equipped with a touch inputoperational portion.

Also, in the above structures, the second display device may speciallydisplay a character or a symbol without a high resolution screen. Ifsuch a structure is obtained, the first display device has a higherresolution than that of the second display device, and thus an increasein cost is suppressed. For example, an electric device in which a TFTformed of a semiconductor layer of polysilicon is used for the firstdisplay device, and a TFT formed of a semiconductor layer of amorphoussilicon is used for the second display device may be used.

Also, in the above structures, an image pickup device or a sensor may beattached to the first display device or the second display device, orprovided in each pixel.

Also, in the above structures, the first display device or the seconddisplay device may be equipped with a system for identifying the user.

Also, in the above structures, the first display device, the seconddisplay device, or the third display device may be suitably a liquidcrystal display device or an EL display device. Further, as the firstdisplay device, the second display device, or the third display device,another display device, for example, an electrochemical display, a fieldemission display, a plasma display, a DMD, or the like can be used.

In still another aspect of the present invention, there is provided aportable electronic device comprising:

a cover member having an EL display device for displaying an image; and

a reflection display device,

wherein the cover member and the reflection display device are attachedto each other so as to allow opening and closing and the reflectiondisplay device is made to display by irradiating light emitted from theEL display device.

In the above structure, the reflection display device may be equippedwith a touch input operational portion.

Also, in the above structures, the portable electronic device is aelectronic device having a communication function, and typically is amobile telephone or a personal digital assistant.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1C are a top view, a side view, and a perspective view ofthe present invention (Embodiment 1), respectively;

FIG. 2 is a top view of the present invention (Embodiment 2);

FIGS. 3A to 3C show switched screens;

FIGS. 4A and 4B are a side view and a perspective view of the presentinvention (Embodiment 3), respectively;

FIG. 5 is a perspective view of the present invention (Embodiment 4);

FIG. 6 is across sectional structure view of an active matrix liquidcrystal display device (Embodiment 5);

FIG. 7 is a top view of an active matrix liquid crystal display device(Embodiment 5);

FIGS. 8A and 8B are circuit block diagrams;

FIGS. 9A and 9B are a top view and a cross sectional view of an activematrix liquid crystal display device (Embodiment 6), respectively;

FIG. 10 is a cross sectional view of an active matrix EL display device(Embodiment 7);

FIGS. 11A and 11B are a top view and across sectional view of an activematrix liquid crystal display device (Embodiment 7), respectively;

FIG. 12 is a circuit block diagram (Embodiment 8);

FIG. 13 is a circuit block diagram (Embodiment 9);

FIG. 14 is a cross sectional view of an EL display device (Embodiment9); and

FIG. 15 is a circuit block diagram (Embodiment 10).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment mode of the present invention will be described below.

FIGS. 1A to 1C are a top view, a side view, and a perspective view,respectively, of a mobile telephone as one example of a portableelectronic device according to the present invention.

The mobile telephone shown in FIG. 1A to 1C has a first display device101 mainly for color-display of an image with high image quality and asecond display device 102 for displaying mainly characters or symbols.

Also, at least one of the first display device 101 and the seconddisplay device 102 has a touch input operational portion. The screen inwhich the touch input operational portion is provided has the functionof an operational switch.

The electronic equipment shown in FIGS. 1A to 1C is a portableelectronic device in which a cover member having the first displaydevice 101 for displaying an image (digital still image or the like) andthe second display device 102 having the touch input operational portion(for displaying characters, symbols, or the like) are attached to eachother so as to allow opening and closing. The mobile telephone shown inFIGS. 1A to 1C is collapsible. The present invention can be implementedin a mode shown in FIG. 2. However, since the display portion can beprotected, the collapsible mobile telephone as shown in FIGS. 1A to 1Cis preferable.

Also, in the case of the collapsible mobile telephone shown in FIGS. 1Ato 1C, an EL display device may be used as the first display device 101and a reflection liquid crystal display device may be used as the seconddisplay device 102. In this case, when the display screen of the firstdisplay device 101 is brought close to the second display device 102 bylight folding, even under low light conditions, the screen of the seconddisplay device 102 can be visually identified utilizing the lightemitted from an EL element in the first display device 101.

Also, the electronic device shown in FIGS. 1A to 1C has severaloperational buttons 103, a voice output portion 104, a voice inputportion 105, and an antenna 106.

Also, as shown in FIG. 2, a portable electronic device may be one inwhich a first display device 204 for displaying an image and a seconddisplay device 205 having a touch input operational portion are attachedto each other in a longitudinal arrangement.

Also, as shown in FIGS. 4A and 4B, a portable electronic device may beone in which a first display device 401 and a second display device 402are attached to each other so as to allow opening and closing with athird display device 403 therebetween.

Also, as shown in FIG. 5, a portable electronic device may be equippedwith an image input portion 507 such as a CCD image pickup device.

Also, the first display device 401, the second display device 402, orthe third display device 403 may be provided with a sensor forauthentication of users. As the authentication of users, living bodyinformation (typically, fingerprint, palmar pattern, voice print, or thelike) may be utilized.

Note that a liquid crystal display device or an EL display device can beused as the first display device 401, the second display device 402, orthe third display device 403.

In the present invention with the above structure, embodiments indicatedbelow will be described in detail.

[Embodiment 1]

In this embodiment, the collapsible portable electronic device shown inFIGS. 1A to 1C will be described. FIG. 1A is a top view, FIG. 1B is aside view, and FIG. 1 c is a perspective view.

In FIGS. 1A to 1C, reference numeral 101 denotes a first display device,numeral 102 denotes a second display device, numeral 103 denotes anoperational switch, numeral 104 denotes a voice output portion, numeral105 denotes a voice input portion, and numeral 106 denotes an antenna.

In this embodiment, an EL display device capable of displaying an imagewith high quality is used as the first display device 101 and a liquidcrystal display device is used as the second display device 102. Also, atouch panel system is employed for the second display device 102. In thecase of the liquid crystal display device, it is necessary to convert areceived digital signal into an analog signal. However, when the ELdisplay device is used as the first display device 101, since a digitalimage can be displayed without such conversion, the EL display device ispreferable. Note that, when a piezoelectric element is incorporated intothe second display device, that is, the liquid crystal display device, atouch panel can be realized.

FIG. 3A shows an example of an initial screen in the second displaydevice 102. A telephone button, electronic mail button, an Internetbutton, a telephone book button, a memory button, and the like aredisplayed on the second display device 102.

For example, when the telephone button displayed on the second displaydevice 102 is pushed, the screen is switched to display dial buttons asshown in FIG. 3B. When the telephone number of the party on the otherend is inputted using the displayed dial buttons, a telephone call tothe party is allowed. When inputting the telephone number, it isdesirable that the inputted number is displayed on the first displaydevice 101 or the second display device 102.

Also, when the telephone book button displayed on the second displaydevice 102 is pushed, a telephone number of the party on the other end,which is inputted in advance, is displayed and thus a telephone call isallowed. At this time, the telephone book may be displayed on the screenof the first display device 101 shown in FIGS. 1A to 1C.

When an electronic mail button or an Internet button, which is displayedon the second display device 102, is pushed, the screen is switched todisplay keyboard buttons as shown in FIG. 3C. The address of anelectronic mail or a URL (uniform resource locator) of a home page canbe inputted using the displayed keyboard buttons. When portionscorresponding to the displayed various input keys are touched, itsdisplay content data can be inputted. Note that the keyboard buttons canbe suitably switched to a screen capable of inputting a capital letter,a lowercase letter, or a numeral. Also, Japanese characters can beinputted. At this time, it is desirable that the inputted number (data)is displayed on the first display device 101 or the second displaydevice 102.

Also, when the telephone book button displayed on the second displaydevice 102 is pushed, the address of the electronic mail, which isinputted in advance, is outputted and thus the electronic mail can betransmitted, or the URL of a home page is outputted and thus the homepage can be referred to. At this time, the telephone book may bedisplayed on the screen of the first display device 101 shown in FIGS.1A to 1C.

When the electronic mail to which an image such as a photograph or apicture is attached is received by the mobile telephone of thisembodiment, the image is displayed on the first display device 101capable of displaying an image with high quality, and characters andsymbols in a text form can be displayed on the second display device102. Also, while the image is displayed on the first display device 101,only data displayed on the screen of the second display device 102 isscrolled and thus a text can be read.

Also, not only the electronic mail to which an image is attached butalso an electronic mail to which voice data is attached can be received.

For example, when a user views a home page by using the mobile telephoneof this embodiment, an image such as a photograph or a picture on publicview is displayed on the first display device 101 capable of displayingan image with high quality. Also, characters (text) indicating theexplanation of the image, the message, or the like of the image aredisplayed on the second display device 102.

According to the present invention, both the image and the characters(text) can be simultaneously and easily viewed by using the mobiletelephone.

Also, as in this embodiment, when the EL display device is used as thefirst display device 101 and the reflection type liquid crystal displaydevice is used as the second display device 102, the display screen ofthe first display device 101 is made to be closer to the second displaydevice 102 by light folding, and, even under low light conditions, thescreen of the second display device 102 can be visually identifiedutilizing the light emitted from an EL element in the first displaydevice 101.

Note that in this embodiment the example is shown in which the ELdisplay device is used as the first display device 101 and the liquidcrystal display device is used as the second display device 102.However, this should not be construed restrictively. A liquid crystaldisplay device or an EL display device can be suitably used as the firstdisplay device 101 or the second display device 102.

[Embodiment 2]

The collapsible portable electronic device is described in Embodiment 1.In Embodiment 2, as shown in FIG. 2, a portable electronic device, inwhich a first display device 204 for displaying an image and a seconddisplay device 205 having a touch input operational portion are attachedto each other in a longitudinal arrangement, will be described.

Note that this embodiment is the same structure as Embodiment 1 exceptfor the configuration of the main body. Thus, a detailed descriptionthereof will be omitted here.

In FIG. 2, reference numeral 201 denotes a main body, numeral 202denotes a voice output portion, numeral 203 denotes a voice inputportion, numeral 206 denotes an image of an operational switch, which isdisplayed on the second display device 205, numeral 207 denotes anoperational switch, and numeral 208 denotes an antenna.

Note that the liquid crystal display device or the EL display device canbe used as the first display device 204 or the second display device205.

[Embodiment 3]

In this embodiment, an example of a portable electronic device havingtwo or more display devices will be described. FIG. 4A is a side viewand FIG. 4B is a perspective view. Note that this embodiment is the samestructure as Embodiment 1 except for the number of display devices.Thus, a detailed description thereof will be omitted here.

As shown in FIGS. 4A and 4B, the portable electronic device of thepresent embodiment is a portable electronic device in which a firstdisplay device 401 and a second display device 402 are attached to eachother so as to allow opening and closing with a third display device 403therebetween.

In FIG. 4A, reference numeral 404 denotes an operational switch, numeral405 denotes a voice output portion, numeral 406 denotes a voice inputportion, and numeral 407 denotes an antenna.

Also, the first display device 401, the second display device 402, orthe third display device 403 may be provided with a sensor forauthentication of users. As the authentication of users, living bodyinformation (typically, fingerprint, palmar pattern, voice print, or thelike) may be utilized.

Note that the liquid crystal display device or the EL display device canbe used as the first display device 401, the second display device 402,or the third display device 403.

[Embodiment 4]

In this embodiment, an example of a portable electronic device having animage pickup device will be described. FIG. 5 is a perspective view.

Note that this embodiment is the same structure as Embodiment 1 exceptthat an image pickup device to is provided. Thus, a detailed descriptionthereof will be omitted here.

In FIG. 5, reference numeral 501 denotes a first display device, numeral502 denotes a second display device, numeral 503 denotes an operationalswitch, numeral 504 denotes a voice output portion, numeral 505 denotesa voice input portion, numeral 506 denotes an antenna, and numeral 507denotes an image input portion.

In this embodiment, a CCD image pickup device is used as the image inputportion 507. Thus, while the user's face image is transmitted to theparty on the other end and the face image of the other end is receivedfrom the party, a telephone call is permitted in the same manner as thenormal conversation.

Also, this embodiment can be combined with any one of Embodiments 1 to3.

[Embodiment 5]

In this embodiment, an example of a liquid crystal display device as thefirst display device or the second display device, which is shown inEmbodiments 1 to 4, will be described.

An example of the liquid crystal display device having a pixel portionand a driver circuit for driving it on a substrate (note that it is in astate before a liquid crystal material sealing) is shown in FIG. 6.

Note that a CMOS circuit as a basic unit is shown as the driver circuitand one pixel is shown as the pixel portion.

In FIG. 6, a driver circuit 601 composed of n-channel TFTs 605 and 606and p-channel TFTs 603 and 604 and a pixel portion 602 composed of apixel TFT 607 as an n-channel TFT and a retaining capacitor 608 areformed on a substrate. Also, in this embodiment, all TFTs are formed astop gate TFTs.

Also, the pixel TFT 607 has a structure (double gate structure) wheretwo channel forming regions are located between a source region and adrain region. However, this embodiment is not limited to the double gatestructure. A single gate structure where one channel forming region isformed or a triple gate structure where three channel forming regionsare formed may be used.

Also, in this embodiment, a pixel electrode connected with the drainregion of the pixel TFT 607 is formed as a reflection electrode. As thematerial of the pixel electrode 610, it is desirable that a materialwith superior reflectivity, such as a film containing mainly Al or Ag ora laminate film of these be used. Also, it is preferable that after theformation of the pixel electrode, its surface is made uneven by aprocess using a sandblast method, an etching method, or the like, whichis known. Thus, mirror reflection is prevented and reflection light isscattered to increase the degree of whiteness.

Note that in this embodiment, the example of the reflection liquidcrystal display device using the reflection electrode as the pixelelectrode is shown. However, a transmission liquid crystal displaydevice using a transparent conductive film as the pixel electrodeinstead of the reflection electrode may be used.

After the state in FIG. 6 is obtained, an orientation film is formed onthe pixel electrode and then rubbing processing is performed. Note thatin this embodiment, before the formation of the orientation film, anorganic resin film such as an acrylic resin film is patterned to formcolumn-shaped spacers for keeping a substrate interval in predeterminedpositions. Instead of the column-shaped spacers, spherical spacers maybe dispersed over the entire surface of the substrate.

Next, a counter substrate is prepared. After colored layers and a lightshielding layer are formed on the counter substrate, a planarizationfilm is formed. Then, a counter electrode made of a transparentconductive film is formed in at least the pixel portion on theplanarization film, an orientation film is formed on the entire surfaceof the counter substrate, and rubbing processing is performed.

Then, a stainless substrate in which the pixel portion and the drivercircuit are formed and a fixing substrate are adhered to each otherthrough an adhesion layer (seal member in this embodiment). Fillers aremixed with the adhesion layer. The two substrates are adhered to eachother at a uniform interval by the fillers and the column-shapedspacers. After that, a liquid crystal material is injected between bothsubstrates and completely sealed using a sealing agent (not shown). Aknown liquid crystal material may be used as the liquid crystalmaterial.

Next, after the liquid crystal sealing (or filling) process iscompleted, a substrate holder is separated as described in theembodiment mode and in Embodiment 1. A state of the liquid crystaldisplay device after that will be described using FIG. 7.

In the top view shown in FIG. 7, a stainless substrate 82 a and acounter substrate 82 b in which a color filter and the like are providedare adhered to each other through a seal member 83. In the stainlesssubstrate 82 a, a pixel portion, driver circuits, an external inputterminal 80 to which an FPC (flexible printed circuit) 89 is adhered,wiring 81 for connecting the external input terminal with input portionsof the respective circuits, and the like are formed.

A light shielding layer 86 a is provided on the counter substrate sideso as to overlap a gate side driver circuit 84 and a light shieldinglayer 86 b is formed on the counter substrate side so as to overlap asource side driver circuit 85. Also, in a color filter 88 which isprovided on the counter substrate on a pixel portion 87, the lightshielding layers and colored layers of respective colors of red (R),green (G), and blue (B) are provided corresponding to each pixel. Inactual display, color display is made by three colors of the red (R)colored layer, the green (G) colored layer, and the blue (B) coloredlayer. The colored layers of the respective colors are arbitrarilyarranged.

In this embodiment, the color filter 88 is provided in the countersubstrate for colorization. However, in particular, the presentinvention is not restricted to this. When an element is formed on asubstrate, a color filter may be formed over the substrate.

Also, the light shielding layer is provided between adjacent pixels inthe color filter to light-shield a portion except for a display region.Further, the light shielding layers 86 a and 86 b are provided in aregion covering the driver circuits. However, when the liquid crystaldisplay device is incorporated as the display portion of the electronicequipment, the region covering the driver circuits is covered with acover. Thus, a structure where the shielding layers are not provided maybe used. When a necessary element is formed on a substrate, lightshielding layers may be formed on the substrate.

Also, without providing the above light shielding layers, the coloredlayers composing the color filter may be suitably arranged between thecounter substrate and the counter electrode such that light shielding ismade with a laminate layer in which a plurality of layers are laminated.Thus, a portion (gap between respective pixel electrodes) except for thedisplay region and the driver circuits are light-shielded.

Also, an FPC 89 made of a base film and wiring is adhered to theexternal input terminal through an anisotropic conductive resin. Areinforced plate is further provided to improve the mechanical strength.

Also, a polarization plate (not shown) is adhered to only the countersubstrate.

The liquid crystal display device thus manufactured can be used as thefirst display device or the second display device in various electronicequipments described in Embodiments 1 to 4.

Also, the liquid crystal display device of this embodiment can be usedas the third display device of Embodiment 3.

An example of a circuit structure of the liquid crystal display deviceof this embodiment is shown in FIGS. 8A and 8B.

Note that FIG. 8A shows a circuit structure for analog drive. In thisembodiment, the liquid crystal display device has a source side drivercircuit 90, a pixel portion 91, and a gate side driver circuit 92. Notethat the term driver circuit in this specification covers the sourceside driver circuit and the gate side driver circuit.

In the source driver circuit 90, a shift register 90 a, a buffer 90 b,and a sampling circuit (transfer gate) 90 c are provided. Also, in thegate side driver circuit 92, a shift register 92 a, a level shifter 92b, and a buffer 92 c are provided. If necessary, a level shifter circuitmay be provided between the sampling circuit and the shift register.

Also, in this embodiment, the pixel portion 91 includes a plurality ofpixels and a TFT element is provided for the respective pixels.

Also, the source side driver circuit 90 and the gate side driver circuit92 can be formed using p-channel TFTs or n-channel TFTs.

Note that, although not shown, another gate side driver circuit may beprovided on the opposite side of the gate side driver circuit 92 withthe pixel portion 91 therebetween.

Also, in the case of digital drive, as shown in FIG. 8B, instead of thesampling circuit, a latch (A) 93 b and a latch (B) 93 c may be provided.In a source side driver circuit 93, a shift register 93 a, the latch (A)93 b, the latch (B) 93 c, a D/A converter 93 d, and a buffer 93 e areprovided. Also, in the gate side driver circuit 95, a shift register 95a, a level shifter 95 b, and a buffer 95 c are provided. If necessary, alevel shifter circuit may be provided between the latch (B) 93 c and theD/A converter 93 d.

Also, although only the structures of the pixel portion 91 or 94 and thedriver circuit are described in this embodiment, a memory or amicroprocessor further may be formed.

[Embodiment 6]

In this embodiment, an example, in which the TFT used for a pixelportion and driver circuits in the liquid crystal display device as thefirst display device or the second display device is formed by aninverse stagger TFT, is shown in FIGS. 9A and 9B. FIG. 9A is a top viewin the case where one of pixels in the pixel portion is enlarged and asectional view taken along a dot line A-A′ in FIG. 9A is shown in FIG.9B. Note that in FIG. 9B, reference numeral 51 denotes a substratehaving an insulating surface.

In the pixel portion, a pixel TFT portion is formed of n-channel TFTs. Agate electrode 52 is formed on a substrate 51, and a first insulatingfilm 53 a of silicon nitride and a second insulating film 53 b ofsilicon oxide are provided thereon. As active layers on the secondinsulating film 53 b, n⁺ type regions 54 to 56, channel forming regions57 and 58, and n⁻ type regions 59 and 60 located between the n⁺ typeregions and the channel forming regions are formed. The channel formingregions 57 and 58 are protected by insulating layers 61 and 62. Aftercontact holes are formed in a first interlayer insulating film 63 whichcovers the insulating layers 61 and 62 and the active layers, wiring 64connected with the n⁺ type region 54 is formed, a pixel electrode 65 ofAl, Ag, or the like is connected with the n⁺ type region 56, and apassivation film 66 is formed thereon. Reference numeral 70 denotes apixel electrode adjacent to a pixel electrode 65.

Note that in this embodiment, the gate wiring of the pixel TFT in thepixel portion is formed in a double gate structure. However, amulti-gate structure such as a triple gate structure may be used inorder to reduce a variation in an off current. Further, a single gatestructure may be used to improve an aperture ratio.

Also, a capacitor portion in the pixel portion is composed of the firstinsulating film 53 a and the second insulating film 53 b as dielectric,capacitor wiring 71, and the n⁺ type region 56.

Note that the pixel portion shown in FIGS. 9A and 9B is merely shown asone example, and the present invention is not restricted to the abovestructure in particular.

Also, this embodiment can be combined with any one of Embodiments 1 to5.

[Embodiment 7]

In this embodiment, an example of an EL (electroluminescence) displaydevice as the first display device or the second display device, whichis shown in Embodiments 1 to 4 will be described.

An example of a light emitting device having a pixel portion and adriver circuit for driving it on the same substrate (note that a statebefore sealing) is shown in FIG. 10. Note that a CMOS circuit as a basicunit is shown in the driver circuit and one pixel is shown in the pixelportion.

In FIG. 10, reference numeral 701 denotes a substrate. An insulatingfilm is formed on the substrate. A driver circuit 704 composed of ann-channel TFT and a p-channel TFT, and a pixel portion 705 comprising aswitching TFT 702 composed of the a p-channel TFT and a current controlTFT 703 composed of an n-channel TFT are formed thereon. Also, in thisembodiment, all TFTs are formed as top gate TFTs.

Also, the switching TFT 702 has a structure (double gate structure)where two channel forming regions are located between a source regionand a drain region. However, this embodiment is not restricted to thedouble gate structure. A single gate structure where one channel formingregion is formed or a triple gate structure where three channel formingregions are formed may be used.

Also, before a second interlayer insulating film 708 is provided, acontact hole is provided in a first interlayer insulating film 707 on adrain region 706 of the current control TFT 703. This is because anetching process is simplified in the case where a contact hole is formedin the second interlayer insulating film 708. The contact hole is formedin the second interlayer insulating film 708 so as to reach the drainregion 706 and a pixel electrode 709 connected with the drain region 706is provided. The pixel electrode 709 is an electrode which functions asthe cathode of an EL element and formed using a conductive filmcontaining an element belonging to group 1 or 2 of the periodic table.In this embodiment, a conductive film made of a compound of lithium andaluminum is used.

Next, reference numeral 713 denotes an insulating film provided to coverend portions of the pixel electrode 709 and this insulating film iscalled a bank in this specification. The bank 713 may be formed using aninsulating film containing silicon or a resin film. In the case wherethe resin film is used, when a carbon particle or a metal particle isadded to the resin film such that resistivity thereof becomes 1×10⁶ to1×10¹² Ωm (preferably, 1×10⁸ to 1×10¹⁰ Ωm), the occurrence of dielectricbreakdown at film formation can be suppressed.

Also, an EL element 710 is composed of the pixel electrode (cathode)709, an EL layer 711, and an anode 712. As the anode 712, a conductivefilm having a large work function, typically an oxide conductive film isused. As the oxide conductive film, indium oxide, tin oxide, zinc oxideor a compound of these may be used. The light emitting device of thisembodiment becomes a light emitting device for emitting light upward.Note that this embodiment is not restricted to the light emitting devicefor emitting light upward. If the structure of the light emitting deviceis suitably modified, the light emitting device for emitting lightdownward can be obtained.

Note that a laminate in which a hole injection layer, a hole transportlayer, a hole blocking layer, an electron transport layer, an electroninjection layer, or an electron blocking layer is combined with aluminescent layer is defined as an EL layer in this specification.

Also, if an EL material is used, the luminescent layer is not limited toa specific material. For example, a thin film made of a luminescentmaterial (singlet compound) for luminescence by singlet excitation or athin film made of a luminescent material (triplet compound) forluminescence by triplet excitation can be used.

Note that, although not shown here, after the anode 712 is formed, it iseffective that a passivation film is provided so as to completely coverthe EL layer 710. As the passivation film, an insulating film includinga carbon film, a silicon nitride film, or a silicon oxynitride film as asingle layer, or a laminate layer of those is used.

Next, a process up to a sealing (or filling) process for protecting theEL element is performed. The EL display device after the process will bedescribed using FIGS. 11A and 11B.

FIG. 11A is a top view showing a state where a process up to sealing ofthe EL element is performed and FIG. 11B is a cross sectional view takenalong a line A-A′ in FIG. 11A. As shown by dot lines, reference numeral801 denotes a pixel portion, numeral 802 denotes a source side drivercircuit, and numeral 803 denotes a gate side driver circuit. Also,reference numeral 804 denotes a cover member, numeral 805 denotes afirst seal member, and numeral 806 denotes a second seal member.

Note that reference numeral 807 denotes wiring for transmitting signalsto be inputted to the source side driver circuit 802 and the gate sidedriver circuit 803. The wiring 807 receives video signals and a clocksignal from an FPC (flexible printed circuit) 808 as an external inputterminal. Note that, although only the FPC is shown here, a printedwiring board (PWB) may be attached to the FPC.

Next, the cross sectional structure will be described using FIG. 11B.The pixel portion and the source side driver circuit 809 are formed overa substrate 800. The pixel portion is composed of a plurality of pixels.Each of the pixels includes a current control TFT 810 and a pixelelectrode electrically connected with the drain thereof. The source sidedriver circuit 809 is constructed using a CMOS circuit in which ann-channel TFT and a p-channel TFT are combined with each other. Notethat a polarization plate (typically a circular polarization plate) maybe attached to the substrate 800.

Also, banks 812 are formed at both ends of the pixel electrode 811 andan EL layer 813 and an anode 814 of the EL element are formed on thepixel electrode 811. The anode 814 also function as wiring common to allpixels and is electrically connected with an FPC 816 through aconnection wiring 815. Further, all elements included in the pixelportion and the source side driver circuit 809 are covered with apassivation film (not shown).

Also, the cover member 804 is adhered to the substrate 800 through thefirst seal member 805. Note that spacers may be provided to secure aninterval between the cover member 804 and the EL element constant. A gap(space) 817 is produced inside the first seal member 805 and thesubstrate 800. It is desirable that the first seal member 805 is amaterial to which moisture or oxygen is not transmitted. Further, it iseffective that a substance having a hygroscopic effect or a substancehaving an antioxidant effect is provided in the gap 817.

Note that a carbon film (specifically, a diamond like carbon film) ispreferably provided as a protective film on the front surface and therear surface of the cover member 804 with a thickness of 2 to 30 nm.Such a carbon film (not shown here) has the functions of preventingpenetration of oxygen and water and mechanically protecting the surfaceof the cover member 804.

After the adhesion of the cover member 804, the second seal member 806is provided so as to cover the exposed surface of the first seal member805. The same material as the first seal member 805 can be used for thesecond seal member 806.

When the EL element is filled with the above structure, the EL elementcan be completely shielded from the exterior and the penetration of asubstance which causes deterioration of the EL layer by oxidation, suchas moisture or oxygen, from the exterior can be prevented. Therefore,the EL display device having high reliability is obtained.

The EL display device manufactured as described above can be used as thefirst display device or the second display device in various electronicequipment described in Embodiments 1 to 4.

Also, the EL display device of this embodiment can be used as the thirddisplay device in Embodiment 3.

[Embodiment 8]

In this embodiment, the structure of an external circuit connected withthe second display device in Embodiment 1 will be described using FIG.12.

In a liquid crystal display device shown in FIG. 12, a pixel portion 921composed of a pixel 920 driven by a TFT formed on a substrate, and asource side driver circuit 915 and a gate signal side driver circuit 914used for driving the pixel portion are formed. The source side drivercircuit 915 is shown as an example of digital drive and constructed by ashift register 916, latch circuits 917 a and 917 b, a D/A converter 918,and buffer circuit 919. Also, the gate signal side driver circuit 914has a shift register, a buffer, and the like (not shown).

An external circuit connected with the liquid crystal display device isconstructed by a power source circuit 901 composed of a stabilized powersource and an operational amplifier with a high speed and highprecision, an external interface port 902 having a USB terminal and thelike, a CPU 903, a touch input tablet 910 used as an input means, adetection circuit 911, a clock signal oscillator 912, a control circuit913, and the like. Note that the touch input tablet 910 (and thedetection circuit 911) may be integrally formed in the inner portion ofthe second display device.

The CPU 903 includes an image signal processing circuit 904, a tabletinterface 905 for inputting a signal from a touch input tablet 910, andthe like. A VRAM 906, a DRAM 907, a flash memory 908, and a memory card909 are connected with the CPU 903. Information processed by the CPU 903is outputted as an image signal from the image signal processing circuit904 to the control circuit 913. The control circuit 913 has the functionof converting the image signal and a clock into respective timingspecifications of the source side driver circuit 915 and the gate signalside driver circuit 914. Specifically, the control circuit 913 has thefunction of distributing the image signal as data corresponding to eachpixel in the display device and the function of converting a horizontalsynchronizing signal and a vertical synchronizing signal, which areinputted from the external, into start signals of the driver circuitsand a timing control signal for alternating a built-in power sourcecircuit.

Also, the control circuit 913 may be mounted using an IC chip by a COGmethod or integrally formed in the inner portion of the liquid crystaldisplay device.

This embodiment can be combined with any one of Embodiments 1 to 6.

[Embodiment 9]

In this embodiment, an example in which an image pickup device (photodiode) is incorporated in each pixel of an EL display device as thefirst display device or the second display device, which is described inEmbodiments 1 to 8, will be described.

FIG. 13 shows the structure of a pixel 1002 in detail. A region enclosedby dot lines is the pixel 1002.

The pixel 1002 has a switching TFT 1004, an EL driving TFT 1005, and anEL element 1006. In FIG. 13, although a capacitor 1007 is provided inthe pixel 1002, the capacitor 1007 may not be provided.

The EL element 1006 is composed of an anode, a cathode, and an EL layerprovided between the anode and the cathode. When the cathode isconnected with the source region or the drain region of the EL drive TFT1005, the anode becomes the counter electrode and the cathode becomesthe pixel electrode, and thus light is emitted downward. On the otherhand, when the anode is connected with the source region or the drainregion of the EL drive TFT 1005, the anode becomes the pixel electrodeand the cathode becomes the counter electrode, and thus light is emittedupward.

The gate electrode of the switching TFT 1004 is connected with a gatesignal line G. With respect to the source region and the drain region ofthe switching TFT 1004, one region is connected with a source signalline S and the other region is connected with the gate electrode of theEL drive TFT 1005.

The source region of the EL drive TFT 1005 is connected with a powersupply line V and the drain region thereof is connected with the ELelement 1006. The capacitor 1007 is connected with the gate electrode ofthe EL drive TFT 1005 and the power supply line V.

Further, the pixel 1002 has a reset TFT 1010, a buffer TFT 1011, aselection TFT 1012, and a photo diode 1013.

The gate electrode of the reset TFT 1010 is connected with a reset gatesignal line RG. The source region of the reset TFT 1010 is connectedwith a sensor power source line VB. The sensor power source line VB isalways kept to be a constant potential (standard potential). Also, thedrain region of the reset TFT 1010 is connected with the photo diode1013 and the gate electrode of the buffer TFT 1011.

Although not shown, the photo diode 1013 has an N-type semiconductorlayer, a P-type semiconductor layer, and a photoelectric conversionlayer provided between the N-type semiconductor layer and the P-typesemiconductor layer. Specifically, the drain region of the reset TFT1010 is connected with, the P-type semiconductor layer or the N-typesemiconductor layer of the photo diode 1013.

The drain region of the buffer TFT 1011 is connected with the sensorpower source line VB and always kept to be a constant standardpotential. The source region of the buffer TFT 1011 is connected withthe source region or the drain region of the selection TFT 1012.

The gate electrode of the selection TFT 1012 is connected with a sensorgate signal line SG. With respect to the source region and the drainregion of the selection TFT 1012, one region is connected with thesource region of the buffer TFT 1011 as described above and the otherregion is connected with a sensor output wiring SS. The sensor outputwiring SS is connected with a constant current power source 1003 and aconstant current always flows into the sensor output wiring SS.

FIG. 14 shows a cross sectional view of this embodiment. Referencenumeral 1101 denotes a switching TFT, numeral 1102 denotes an EL drivingTFT, numeral 1103 denotes a reset TFT, numeral 1104 denotes a bufferTFT, and numeral 1105 denotes a selection TFT.

Also, reference numeral 1108 denotes a P-type semiconductor layer,numeral 1109 denotes a photoelectric conversion layer, and numeral 1107denotes an N-type semiconductor layer. A photo diode 1106 is formed ofthe P-type semiconductor layer 1108, the photoelectric conversion layer1109, and the N-type semiconductor layer 1107. Reference numeral 1111denotes a sensor wiring and the sensor wiring 1111 is used toelectrically connect the N-type semiconductor layer 1107 with anexternal power source. The P-type semiconductor layer 1108 of the photodiode 1106 is electrically connected with the drain region of the resetTFT 1103.

Also, reference numeral 1110 denotes a pixel electrode (anode), numeral1112 denotes an EL layer, and numeral 1113 denotes a counter electrode(cathode). An EL element 1114 is composed of the pixel electrode (anode)1110, the EL layer 1112, and the counter electrode (cathode) 1113. Notethat reference numeral 1115 indicates a bank and the EL layers 1112 ofadjacent pixels are separated by the bank.

Reference numeral 1116 denotes an object to be photographed. Lightemitted from the EL element 1114 is reflected by the object 1116 to bephotographed and irradiated into the photo diode 1106. In thisembodiment, the object to be photographed is provided at the side of thesubstrate 1100, where the TFTs are not formed.

In this embodiment, the switching TFT 1101, the buffer TFT 1104, and theselection TFT 1105 are all N-channel TFTs. Also, the EL driving TFT 1102and the reset TFT 1103 are P-channel TFTs. Note that the presentinvention is not restricted to this structure. Thus, the switching TFT1101, the EL driving TFT 1102, the buffer TFT 1104, the selection TFT1105, and the reset TFT 1103 may be any one of N-channel TFTs andP-channel TFTs.

Note that, as described in this embodiment, when the source region orthe drain region of the EL driving TFT 1102 is electrically connectedwith the anode 1110 of the EL element 1114, it is desirable that the ELdriving TFT 1102 is a P-channel TFT. On the other hand, when the sourceregion or the drain region of the EL driving TFT 1102 is electricallyconnected with the cathode of the EL element 1114, it is desirable thatthe EL driving TFT 1102 is an N-channel TFT.

Note that, since the photo diode of this embodiment can besimultaneously formed together with other TFTs, the number of processescan be decreased.

This embodiment can be combined with any one of Embodiments 1 to 7.

[Embodiment 10]

In this embodiment, an example in which a memory element (SRAM) isincorporated in each pixel of an EL display device as the first displaydevice or the second display device, which is described in Embodiments 1to 8, will be described. FIG. 15 is an enlarged view of a pixel 1504.

In FIG. 15, reference numeral 1505 denotes a switching TFT. The gateelectrode of the switching TFT 1505 is connected with a gate signal line1506 as one of gate signal lines (G1 to Gn) for inputting gate signals.With respect to the source region and the drain region of the switchingTFT 1505, one region is connected with a source signal line 1507 as oneof source signal lines (S1 to Sn) for inputting signals and the otherregion is connected with the input side of an SRAM 1508. The output sideof the SRAM 1508 is connected with the gate electrode of a currentcontrol TFT 1509.

With respect to the source region and the drain region of the currentcontrol TFT 1509, one region is connected with a current supply line1510 as one of current supply lines (V1 to Vn) and the other region isconnected with an EL element 1511.

The EL element 1511 is composed of an anode, a cathode, and an EL layerprovided between the anode and the cathode. When the anode is connectedwith the source region or the drain region of the current control TFT1509, in other words, when the anode is a pixel electrode, the cathodebecomes a counter electrode. On the other hand, when the cathode isconnected with the source region or the drain region of the currentcontrol TFT 1509, in other words, when the cathode is a pixel electrode,the anode becomes a counter electrode.

The SRAM 1508 has two p-channel TFTs and two n-channel TFTs. The sourceregions of the p-channel TFTs are connected with Vddh at a high voltageside and the source regions of the n-channel TFTs are connected with Vssat a low voltage side. One p-channel TFT and one n-channel TFT make apair. In one SRAM, two pairs of p-channel TFT and n-channel TFT arepresent.

With respect to a pair of p-channel TFT and n-channel TFT, the drainregions are connected with each other. Also, with respect to a pair ofp-channel TFT and n-channel TFT, the gate electrodes are connected witheach other. The drain regions in one pair of p-channel TFT and n-channelTFT are kept to be the same potential as the gate electrodes in theother pair of p-channel TFT and n-channel TFT.

The drain regions in one pair of p-channel TFT and n-channel TFTconstitute the input side in which an input signal (Vin) is inputted.The drain regions in the other pair of p-channel TFT and n-channel TFTconstitute the output side in which an output signal (Vout) isoutputted.

The SRAM is designed to hold Vin and output Vout as a signal obtained byinverting Vin. That is, when Vin is Hi, Vout becomes a Lo signalcorresponding to Vss. On the other hand, when Vin is Lo, Vout becomes aHi signal corresponding to Vddh.

Note that, as described in this embodiment, when one SRAM is provided inthe pixel 1504, since memory data in the pixel is held, a still imagecan be displayed in a state in which most of the external circuits arestopped. Thus, low power consumption can be realized.

Also, a plurality of SRAMs can be provided in the pixel. When theplurality of SRAMs are provided in the pixel, a plurality of data can beheld. Thus, gradation display with time gradation is possible.

The structure of this embodiment can be freely combined with any one ofthe structures of Embodiments 1 to 9.

According to the present invention, a portion of conventionaloperational buttons is made to be a display screen. Thus, a displayregion can be expanded without changing the outer size of the electronicdevice and much information can be displayed at once.

According to the present invention, both the image and the characters(text) can be simultaneously and easily seen with a high resolution byusing the mobile telephone.

What is claimed is:
 1. A portable electronic device comprising: a firstsubstrate; a second substrate over the first substrate; a pixel portionformed over the first substrate; a touch input operational portion; adetection circuit operationally connected to the touch input operationalportion; a first seal member between the first and second substrates;and a second seal member between the first and second substrates,wherein the second seal member comprises a first region in contact withthe first seal member; wherein the second seal member comprises a secondregion in contact with an end portion of the second substrate, whereinthe pixel portion comprises a pixel, wherein the pixel comprises atleast five TFTs and an EL element, wherein the EL element comprises afirst electrode and a second electrode, wherein the first electrode iselectrically connected to one of the five TFTs, wherein the EL elementis covered with a first film, wherein an end portion of the firstelectrode is covered with a second film.
 2. The portable electronicdevice according to claim 1, wherein the first electrode is a cathode ofthe EL element.
 3. The portable electronic device according to claim 1,wherein the one of five TFTs is an n-channel TFT.
 4. The portableelectronic device according to claim 1, wherein the first film is apassivation film.
 5. The portable electronic device according to claim1, wherein the first film comprises a carbon film, a silicon nitridefilm, or a silicon oxynitride film.
 6. The portable electronic deviceaccording to claim 1, wherein the first and second seal members comprisea same material.
 7. The portable electronic device according to claim 1,wherein the touch input operational portion is formed in the pixelportion.
 8. The portable electronic device according to claim 1, whereinthe pixel comprises a photo diode.
 9. The portable electronic deviceaccording to claim 1, wherein the EL element comprises an EL layer whichcomprises a triplet compound.
 10. The portable electronic deviceaccording to claim 1, wherein the number of the TFTs in the pixel isfive.
 11. The portable electronic device according to claim 1, whereinthe number of the TFTs in the pixel is six.
 12. A portable electronicdevice comprising: a first substrate; a second substrate over the firstsubstrate; a pixel portion formed over the first substrate; a touchinput operational portion; a detection circuit operationally connectedto the touch input operational portion; a first seal member between thefirst and second substrates; and a second seal member between the firstand second substrates, wherein the second seal member comprises a firstregion in contact with the first seal member; wherein the second sealmember comprises a second region in contact with an end portion of thesecond substrate, wherein the pixel portion comprises a pixel, whereinthe pixel comprises at least five TFTs and an EL element, wherein the ELelement comprises a first electrode and a second electrode, wherein thefirst electrode is electrically connected to one of the five TFTs,wherein the EL element is covered with a first film, wherein an endportion of the first electrode is covered with a second film wherein alight emitted from the EL element is transmitted through the first filmand the second substrate.
 13. The portable electronic device accordingto claim 12, wherein the first electrode is a cathode of the EL element.14. The portable electronic device according to claim 12, wherein theone of five TFTs is an n-channel TFT.
 15. The portable electronic deviceaccording to claim 12, wherein the first film is a passivation film. 16.The portable electronic device according to claim 12, wherein the firstfilm comprises a carbon film, a silicon nitride film, or a siliconoxynitride film.
 17. The portable electronic device according to claim12, wherein the first and second seal members comprise a same material.18. The portable electronic device according to claim 12, wherein thetouch input operational portion is formed in the pixel portion.
 19. Theportable electronic device according to claim 12, wherein the pixelcomprises a photo diode.
 20. The portable electronic device according toclaim 12, wherein the EL element comprises an EL layer which comprises atriplet compound.
 21. The portable electronic device according to claim12, wherein the number of the TFTs in the pixel is five.
 22. Theportable electronic device according to claim 12, wherein the number ofthe TFTs in the pixel is six.
 23. A portable electronic devicecomprising: a first substrate; a second substrate over the firstsubstrate; a pixel portion formed over the first substrate; a touchinput operational portion; a detection circuit operationally connectedto the touch input operational portion; a first seal member between thefirst and second substrates; and a second seal member between the firstand second substrates, wherein the second seal member comprises a firstregion in contact with the first seal member; wherein the second sealmember comprises a second region in contact with an end portion of thesecond substrate, wherein the pixel portion comprises a pixel, whereinthe pixel comprises at least five TFTs and an EL element, wherein the ELelement comprises a first electrode and a second electrode, wherein thefirst electrode is electrically connected to one of the five TFTs,wherein a first film is formed over the EL element, wherein an endportion of the first electrode is covered with a second film wherein alight emitted from the EL element is transmitted through the first filmand the second substrate.
 24. The portable electronic device accordingto claim 23, wherein the first electrode is a cathode of the EL element.25. The portable electronic device according to claim 23, wherein theone of five TFTs is an n-channel TFT.
 26. The portable electronic deviceaccording to claim 23, wherein the first film is a passivation film. 27.The portable electronic device according to claim 23, wherein the firstfilm comprises a carbon film, a silicon nitride film, or a siliconoxynitride film.
 28. The portable electronic device according to claim23, wherein the first and second seal members comprise a same material.29. The portable electronic device according to claim 23, wherein thetouch input operational portion is formed in the pixel portion.
 30. Theportable electronic device according to claim 23, wherein the pixelcomprises a photo diode.
 31. The portable electronic device according toclaim 23, wherein the EL element comprises an EL layer which comprises atriplet compound.
 32. The portable electronic device according to claim23, wherein the number of the TFTs in the pixel is five.
 33. Theportable electronic device according to claim 23, wherein the number ofthe TFTs in the pixel is six.